Because she killed herself, Sagiri became one who escorts souls of those who have died, instead of going to heaven. She met Hisagi while he was crossing the river of the world of the dead... They promised they would meet again and live happily in their next lives... Can their promise be fulfilled?

Ugh... I hate plot devices (stuff like the flower message that comes out of nowhere and just exists 'cause the author can not think of a better way to make her character aware).

Spoiler (mouse over to view)

It's pretty clichee: mains fall in love at first sight -> main falls back into her life -> main believes she might be in his time -> wrong -> main believes he might be in her time -> wrong -> depression -> main gets some random flower message from her love -> depression gone -> main goes to the palace to check -> main meets a guy that looks like him -> he does not remember her -> he thinks she is a boy -> he is gay oo